William S. Hart took a respite from his "good-badman" groove to play a preacher in Apostle of Vengeance. David Hudson (William S. Hart), a minister living in Vermont, returns to his home in the Kentucky hills in an attempt to reconcile the members of his family with their bitter rivals, the McCoys. Upon learning of David's peaceful intentions, his family angrily turns him out of the house, whereupon he moves into a little mountain shack and preaches to anyone who will listen. After rescuing Mary McCoy (Nona Thomas) from the hands of a brute, David saves his young sister Elsie (Marvel Stafford) from drowning; but when he discovers that it was Tom McCoy (Joseph J. Dowling) who attacked Elsie, he is finally spurred to violence. David is strangling Tom when he realizes the folly of his vengeance and consequently relaxes his grip. Inspired by David's example, the Hudsons and McCoys finally settle their differences. Hart himself directed Apostle of Vengeance, with second-unit assistance from his faithful cohort Clifford Smith. Future stars John Gilbert and Jean Hersholt show up as extras, just as they did in Hart's Hell's Hinges (1916).

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